Author
Topic: EF-S 15-60 f/2.8 IS [CR1] (Read 43072 times)

One of the reasons you might want to use a faster shutter speed with a 7d is the higher pixel density. Even a tiny movement will show blur at the pixel level, while the much larger pizels of a FF may not get smeared with the same amount of movement.

However, the resultant image viewed at the same print size won't show it, just peeping at 1:1 magnification.

Given Canon's obsession for pixel count over sensitivity, the potential stop gained by f/2.8 compared to f/4 zooms would seem to be countered by the extra ISO step needed for the same noise level compared to a FF unit.

Exactly. Few people get this - especially those who make statements like, "I'm not upgrading to FF until they make a FF equivalent of the 17-55mm f/2.8 IS," in reference to the magical unicorn also known as a 24-70mm f/2.8L IS. In fact, the 24-105mm f/4L IS when used on FF specs out better than the 17-55mm f/2.8 IS on a crop body. The FF-equivalent of the latter is 27-88mm f/4.5 IS, meaning the 24-105mm is wider, longer, and faster. It's true that f/2.8 still yields a faster shutter speed than f/4, since the crop factor doesn't affect exposure (apparent effect is on DoF only), but as you point out - FF has a 1.3-stop advantage in ISO noise, meaning you can bump the shutter speed up a stop by using a higher ISO on FF to match the shutter speed you'd get with f/2.8 on a crop body.

Correct.

But here's another way to look at this. Suppose we want to emulate 17-55/2.8 IS on a FF body. We'll need a 27-88/4.5 IS lens to emulate field-of-view and dof, and we'll crank up the iso by one stop to emulate shutter speed.

So: the 17-55/2.8 IS can do almost the same as a 24-105/4 IS on full-frame. Not quite the same focal length range, just a tad shallower dof, and even with iso up one stop there's still a slight noise advantage. But it's close.

And that's pretty impressive if you think about it, for a sensor that's 2.5x smaller.

So: the 17-55/2.8 IS can do almost the same as a 24-105/4 IS on full-frame. Not quite the same focal length range, just a tad shallower dof, and even with iso up one stop there's still a slight noise advantage. But it's close.

And that's pretty impressive if you think about it, for a sensor that's 2.5x smaller.

So: the 17-55 f/2.8 IS is almost the same as a 24-105 f/4 L IS on a full frame ... except not as good in any of the key competitive areas.

Since making lenses for smaller sensors is supposed to be 1. cheaper and 2. easier than making lenses for large sensors, I'd say those are actually quite lousy stats on the part of the 17-55 f/2.8 IS

Since making lenses for smaller sensors is supposed to be 1. cheaper and 2. easier than making lenses for large sensors

Actually it's the other way around. Making lenses for large format cameras is easier. Case in point: lenses for large view cameras. If you've ever looked at an Ansel Adam print, you're bound to be amazed at the resolution and detail. Yet the lenses he shot with are primitive compared to today's SLR lenses.

Lens construction isn't that one-dimensional.A lens for a small sensor is almost always stopped down to near the limit of diffraction. Its hard to find an EF/EF-s lens that doesn't perform decent at f/8 or f/11. Those compact lenses also get the benefit of doubt in terms of assembly tolerances. Most defects are hidden in DOF, others are taken care of by the image processing or aren't recognized by the target audience. Autofocus from the imaging sensor makes things easier too.

The ancient large format lens had also a hidden ace in the hole - the strong color filtering used in bw photography.All those wavelength dependent flaws our lenses have to deal with are suddenly gone. Being stopped down for sharpness across the frame helps also, f/64 should ring a bell. Being a manual focus prime without IF/RF and built without the stringent budget constraints of consumer lenses is also a factor.

Going for a large zoom range while offering a wide aperture and excellent image quality across the whole frame and zoom range at a competitive price all at the same time is more difficult. Most of the knobs one could use to tweak the other designs are locked down, but in exchange you've got to meet higher standards.

DrPizza

The EF-S 17-55 f/2.8 IS USM is already one of Canon's best lenses (and one where Nikon fails to exercise any competitive pressure). It's ridiculous that it should be a candidate for replacement.

How about introducing a new lens to actually fill a gap? An EF-S 55-150 f/2.8 IS USM, for example. Yes, yes, I know about the various 70-200 Ls. Too big, too heavy, too white. I want smaller, lighter, crop sensor lenses. Something to slot in above the 17-55 would be fabulous.

And how about a few crop sensor primes. A 35mm f/1.4, say...

Logged

DuLt

Wouldn't it be better if instead of a longer range, we got a shorter but higher quality luminous zoom?Say... 15-45 F2.8?Then the 15-85 could be improved to continuous F4... giving us two choices: zoom range vs speed.

Wouldn't it be better if instead of a longer range, we got a shorter but higher quality luminous zoom?Say... 15-45 F2.8?Then the 15-85 could be improved to continuous F4... giving us two choices: zoom range vs speed.

I don't know what a luminous zoom is, nothing on Google either.

All Zoom lenses are a compromise, shorter ones compromise less, but if you get too short a zoom, then you can just use a prime. The biggest market for low cost EF-s zooms is from the Rebel users, who are not camera enthusiasts, they had a long zoom on their P&S, and want one on their DSLR. Even a long Zoom can be a big improvement over a P&S with a superzoom, so the buyer is very happy.

Logged

DuLt

Wouldn't it be better if instead of a longer range, we got a shorter but higher quality luminous zoom?Say... 15-45 F2.8?Then the 15-85 could be improved to continuous F4... giving us two choices: zoom range vs speed.

I don't know what a luminous zoom is, nothing on Google either.

All Zoom lenses are a compromise, shorter ones compromise less, but if you get too short a zoom, then you can just use a prime. The biggest market for low cost EF-s zooms is from the Rebel users, who are not camera enthusiasts, they had a long zoom on their P&S, and want one on their DSLR. Even a long Zoom can be a big improvement over a P&S with a superzoom, so the buyer is very happy.

Luminous zoom as in a faster zoom. Sorry if english is not my main language.And in this sense I though than an EF-S 15-45 F2.8 and an EF-S 15-85 F4 would be the APS-C EF 24-70 F2.8 and EF 24-135 F4 versions.15-45 would give us 24-70mm coverage, it's not that long but it serves my needs.

Luminous zoom as in a faster zoom. Sorry if english is not my main language.And in this sense I though than an EF-S 15-45 F2.8 and an EF-S 15-85 F4 would be the APS-C EF 24-70 F2.8 and EF 24-135 F4 versions.15-45 would give us 24-70mm coverage, it's not that long but it serves my needs.

No problem with Luminous, I thought I had come accross a new term, its actually quite a good one once i know what was meant.

The current 17-55mm IS is a excellent lens, it is a 3.2X zoom, which seems to be a good range for quality zooms. It is not as wide as I'd like, and even a few mm longer would be nice. However, on a light weight Rebel, many users complain of its weight. I found it ideal on a 40D and 7D.

The rumored 15-60mm f/2.8 lens is a 4X lens, and compromises can become more apparent with the longer range. The weight will increase too, unless Canon has a way to lighten it up.